The Role of Faith-Based Organizations in Improving Vaccination Confidence & Addressing Vaccination Disparities to Help Improve Vaccine Uptake: A Systematic Review

The COVID-19 pandemic underscored the importance of vaccination to support individual health across the life-course, with vaccination playing a central strategy role in mitigating transmission and disease. This required unprecedented mobilization and coordination across all sectors to meet people where they are, enable equitable access, and build vaccination confidence. A literature search was conducted with combinations of the keywords and variations of vaccination and faith-based organizations (FBOs). Search inclusion criteria were: (1) FBO programs that supported public health emergency efforts, including vaccination efforts as the primary outcome; and (2) articles written in English language. A total of 37 articles met inclusion criteria (n = 26 focused on general public health campaigns, n = 11 focused on vaccination efforts). The findings related to public health campaigns fell into four themes: FBO’s ability to (1) tailor public health campaigns; (2) mitigate barriers; (3) establish trust; and (4) disseminate and sustain efforts. The findings related to vaccine uptake efforts fell into three themes: (1) pre-pandemic influenza and HPV vaccination efforts, (2) addressing vaccine disparities in minority communities, and (3) enabling COVID-19 vaccination. This review demonstrated that FBOs have a vital role in both public health campaigns and vaccination initiatives to support high vaccine uptake and confidence.


Introduction
As of February 2023, the COVID-19 pandemic has resulted in over 756 million reported cases, over 6.8 million deaths, and has impacted both adults and children around the globe [1]. A silent crisis has emerged as a result of a convergence of factors related to the pandemic; namely the significant decline in routine vaccinations across the life-course, upending decades of progress in achieving and maintaining high vaccination rates. According to World Health Organization (WHO) and United Nations Children's Fund (UNICEF) data, approximately 25 million children missed some routine vaccinations and close to 17 million children did not receive a single vaccine in 2020 [2]. This results in communities being placed at risk of vaccine preventable diseases (VPDs), outbreaks, and certain cancers associated with VPDs. The US has recently seen the reemergence of VPDs such as measles, 121 cases occurring in 2022, and polio, underscoring the critical need to maintain high vaccination rates to curb further disease [3][4][5]. Furthermore, there is a disparate impact and a slower recovery of VPDs for the most vulnerable and underserved populations, widening pre-pandemic disparities [1,[6][7][8][9][10].
Global declines in vaccination coverage rates across the life-course will take years of recovery to return to pre-pandemic levels-and ultimately achieve global and national vaccination targets [10,11]. Projections estimate that for adolescents in the United States, if every provider saw 15% more patients each month, it could take up to seven years to recover certain vaccinations missed during the COVID-19 pandemic [12]. This calls for a comprehensive approach to ensuring vaccination rates not only increase to pre-pandemic levels, but strengthen immunization programs to achieve high vaccine uptake.
As such, the COVID-19 pandemic has compelled communities and immunization programs to generate creative and sustainable solutions to this public health crisis. Often these solutions are deeply embedded in communities, such as faith-based organizations (FBOs). FBOs and faith-based engagement strategies have been the foundation of many previous collective efforts targeting other infectious diseases and public health emergencies [6,7,13]. FBOs are organizations whose philosophies are driven by certain religious beliefs, often including a social or moral component [14]. These entities have been shown to bring people together for positive purposes and can present powerful agents for health and justice [15][16][17][18]. As religion is a social determinant of population health, it functions through the work of social institutions [16]. Therefore, FBOs are key stakeholders in communities; they present a discernible and trusted public face to communities through acts of leadership and capacity for service to others [15,17]. The CDC workbook defines FBOs as "churches, synagogues, mosques, church sponsored service agencies, and all charitable organizations with religious affiliations"-this broad definition can therefore include nonprofit organizations with a religious affiliation or inspiration [18]. FBOs are driven by a desire to provide health care services, combating the growing unmet health care needs in their community [18]. The social capital effects are of importance in communities with minority and low-socioeconomic groups and elsewhere that social and economic resources are limited, such as vaccinations [17].
The public health imperative of going hyperlocal and engaging FBOs and leveraging faith-based engagement is critical as: (1) the pandemic has worsened long-standing vaccination disparities; (2) lower resource regions and countries share a disproportionate burden of low childhood vaccine uptake; (3) public health challenges to global childhood routine vaccination uptake remain. Yet, there is no synthesis of the current literature on this timely topic. Therefore, we present here the latest summary of evidence on the overall role of FBOs in public health efforts and the role of FBOs in vaccination efforts and vaccine disparities.

Search Strategy
PRISMA guidelines were used as the search framework ( Figure 1). A comprehensive search was completed via PUBMED, Web of Science, Science Direct, and COCHRANE. Combinations of the keywords 'vaccination' or 'immunization', 'COVID-19 vaccine', 'childhood vaccination' or 'routine vaccination' and 'faith-based organization' or 'faith-based' were used as search terms. The publication dates of interest were limited to 1 January 2002 through 31 December 2021. The search was run across all databases during January-March 2022. See Supplementary Materials Figure S1 for PRISMA Diagram and additional details regarding the search strategy; Table S1 for sample of quality assessment tool for systematic reviews and meta-analyses by the National Heart, Lung, and Blood Institute; Table S2 for sample of quality assessment tool for observational cohort and cross-sectional studies by the Na-tional Heart, Lung, and Blood Institute; Table S3 for sample of quality assessment tool for controlled intervention studies by the National Heart, Lung, and Blood Institute; and Table S4 and sample of quality assessment tool for case series studies by the National Heart, Lung, and Blood Institute.

Study Selection
Studies were included if they met the following criteria: (1) FBO programs that supported public health emergency efforts, including vaccination efforts, both routine and COVID-19, as the primary outcome; and (2) articles written in English language.
For the context of the study, FBOs were defined as entities associated with or inspired by religion or religious beliefs. Public health campaigns were understood to be an effort to motivate a defined public to participate in behaviors that will improve health or withhold from behaviors that are identified as unhealthy.

Data Extraction
Studies were selected based on a theoretical framework of FBOs and public health interventions ( Figure 2) [15][16][17][18][19]. The theoretical framework proposes FBOs are able to enact public health interventions through four themes: (1) tailor public health campaigns,

Study Selection
Studies were included if they met the following criteria: (1) FBO programs that supported public health emergency efforts, including vaccination efforts, both routine and COVID-19, as the primary outcome; and (2) articles written in English language.
For the context of the study, FBOs were defined as entities associated with or inspired by religion or religious beliefs. Public health campaigns were understood to be an effort to motivate a defined public to participate in behaviors that will improve health or withhold from behaviors that are identified as unhealthy.

Data Extraction
Studies were selected based on a theoretical framework of FBOs and public health interventions ( Figure 2) [15][16][17][18][19]. The theoretical framework proposes FBOs are able to enact public health interventions through four themes: (1) tailor public health campaigns, (2) ability to manage barriers and challenges, (3) dissemination and sustainability, and (4) establishing a community of trust (Table 1). Similarly, we examined the role of FBOs in vaccine uptake specific efforts through three themes: (1) pre-pandemic influenza and HPV vaccination uptake efforts, (2) addressing vaccine disparities in ethnic minority communities, and (3) addressing recent COVID-19 vaccination efforts ( Table 2). The themes listed were developed by identifying the overarching goal of each study and subsequently grouping them based on corresponding goals.
Vaccines 2023, 11, x FOR PEER REVIEW 4 of (2) ability to manage barriers and challenges, (3) dissemination and sustainability, and ( establishing a community of trust (Table 1). Similarly, we examined the role of FBOs i vaccine uptake specific efforts through three themes: (1) pre-pandemic influenza and HP vaccination uptake efforts, (2) addressing vaccine disparities in ethnic minority commu nities, and (3) addressing recent COVID-19 vaccination efforts ( Table 2). The themes liste were developed by identifying the overarching goal of each study and subsequent grouping them based on corresponding goals.

Bopp (2008)
Present practical aspects of intervention planning, implementation and evaluation within common community settings There is a need for process evaluation of intervention implementation to provide valuable information for the dissemination and sustainability of successful interventions Partnering with community settings (schools, worksites, faith-based organizations and healthcare organizations) offers many benefits and the opportunity to reach specific populations     Table 2).
The papers were also organized according to: origin of data collection, purpose, research design, target population, inclusion criteria, summary points, and key points. This helped to map the overall landscape of the literature.
Data extraction was completed by 2 reviewers (O.K. and A.C.). There were no discrepancies between reviewers in terms of data extracted or choice of articles meriting inclusion.
The study did not collect any primary data. The risk of bias in individual studies was analyzed using the Study Quality Assessment Tools developed by the National Heart, Lung, and Blood Institute (NHLBI) [20]. The strength of studies was evaluated based on criteria published by the Oxford Center for Evidence-Based Medicine (OCEBM) [21].

Results
A total of 37 articles were included in the analysis (Figure 1) [6,7,. Results were categorized as "public health interventions", where interventions were related to addressing public health needs across various topics including mental health and physical activity, then "vaccination interventions" which are those focused specifically on supporting vaccine uptake. Results are presented below in order of those based on public health interventions first, then further refined to those focused on vaccination interventions. Table 1 summarizes the articles (n = 26) that were deemed relevant or directly related to FBOs and public health interventions. Of the 26 articles, 14 of the studies were conducted in the United States. The findings in context to public health campaigns and efforts in general are summarized in four themes based on the theoretical framework ( Figure 2): FBO's ability to (1) tailor public health campaigns, (2) ability to manage barriers and challenges, (3) dissemination and sustainability, and (4) establishing a community of trust.

Theme 1: Tailored Public Health Campaigns
Leyva et al. [22] concluded that public health campaigns are not one-size-fits-all for FBOs, and there is a need for tailored strategies to enhance community engagement. Due to the involvement in its members' lives, FBOs can address individual concerns in addition to personalizing the public health campaign, as found in Wasser et al. [23] For utilizing the sense of community within FBOs, Wilson et al. [24] developed a framework for FBOs to create culturally appropriate public health campaigns. Similarly, Blankinship et al. [25] performed a narrative review on faith-based wellness programs in Latino and African American populations and determined FBOs provide culturally appropriate messaging and create community support and self-efficacy, which aid in public health campaigns. Similarly, Sobers et al. [26] showcased FBOs' use of social support to implement evidence-based selfmanagement intervention for hypertension. Ackerman Gulaid and Kiragu [27] provide ten recommendations for community engagement that highlight the need to actively identify and build on a community's efforts.

Theme 2: Ability to Manage Barriers and Challenges
The ability to remove barriers that limit access to care for their members is another attribute of the application of FBOs for public health campaigns. In a retrospective chart review of Hispanic farmworker women in Central Florida, Luque et al. [28] found that FBOs aided in the removal of obstacles that prevent uninsured and low-income populations from receiving and accessing care. Tristão Parra et al. [29] reviewed the use of physical activity interventions delivered by FBOs and concluded FBOs create an environment that encourages physical activity and, therefore, can address health disparities. Similarly, in a review of Asian American FBOs in New York City and New Jersey, Kwon et al. [30] determined that FBOs support public health initiatives that give people who have disproportionately poor health outcomes, access to health promotion programs.
Other studies have shown that FBOs provide their members with various coping strategies to address mental health barriers such as prayer, scripture, social support groups, religious services, and aid from religious leaders, showing a potential opportunity for other health-related dialogue such as vaccination. Rayes et al. [31] performed qualitative interviews on Arabic-speaking refugee populations from Muslim majority countries resettling in Europe. The study found that participants with a stronger devotion to faith were more likely to use faith-based coping mechanisms when handling challenges and seeking mental health services. Similarly, Schieffler and Genig [32], after conducting a mini-narrative review on orthodox church members, found that FBOs play a significant role for its people regarding mental health burdens to heal "both soul and body".

Theme 3: Establishing a Community of Trust
One of the essential aspects of FBOs involvement in public health campaigns is the capability to create a community of trust. Bopp et al. [33] emphasized FBO leaders' role in distributing health promotion interventions. Members entrust their leaders to shape their spiritual, physical, emotional, and social environments. In a narrative review, Maynard [33] concluded FBOs are a central component in neighborhoods, and participation in a faith community persists in many communities.
FBOs play a crucial role in the daily life of African American faith communities. As explored in Francis and Liverpool [35], the adoption of the public health campaigns by faith community leaders influences the adoption in African American communities. Lancaster et al. [36] performed a systematic review on African American FBOs and concluded FBOs could effectively promote health interventions and behaviors in their communities due to the significance of faith to many African Americans.
By creating a community of trust, FBOs provide an ecosystem of aid. FBOs coordinate and collaborate with health professionals, stakeholders, community members, and social groups. Vitillo et al. [37] concluded from their review of the role and contributions of FBOs, private sectors, and philanthropic partners that joint engagement is required to achieve community success. In a review of the relationship between government and FBOs, Brooks and Koenig [19] found partnerships between government and FBOs may create an environment with the most significant health benefit that could not be accomplished solely. Pfefferbaum et al. [38] found partnerships in public health interventions produce the most significant positive impact.

Theme 4: Dissemination and Sustainability
As explored in a mixed-methods study by Grieve and Oliver [39], FBOs are a recognized, valued stakeholder in society, allowing them to collaborate among those in the public sector and various community members. These partnerships allow for an increase in the public health campaign's awareness, longevity, and effect. Bopp and Fallon [40] concluded that partnering with FBOs for public health campaigns presents several advantages and prospects for reaching specific populations. Kaczynski et al. [41] performed a group-randomized trial in which they found FBOs can encourage diverse health outcomes. Additionally, Johnston et al. [42] concluded health outcomes could be improved through public health interventions by FBOs.
For a public health campaign to be sustainable, there needs to be buy-in from community members, policymakers, and other relevant decision makers and stakeholders. With FBOs being a trusted source, FBOs can engage members interested in public health campaigns, as seen by Morad et al. [43], which found involvement of FBOs in public health campaigns engages community participation. Sheikhi et al. [7] concluded FBOs provide avenues for partnership with stakeholders and collaboration with healthcare providers, especially mental health professionals. Tadesse Gebremedhin et al. [44] found that committed leadership by policymakers and "buy-in" from crucial stakeholders allows for the involvement of community members at different levels. In a systematic review, De-Haven et al. [45] provided recommendations for FBOs to increase their effectiveness by encouraging partnerships between FBOs and health professionals to evaluate public health interventions, disseminate findings, and focus on fostering relationships with racially and ethnically diverse populations. Table 2 provides a summary of the role of FBOs in vaccine uptake specific efforts. It must be noted, however, that the literature on vaccination efforts related to COVID-19 vaccines is limited, given that the vaccine has only recently become available for children. In general, the 11 included papers [6,[46][47][48][49][50][51][52][53][54][55] focused on three main themes: (1) pre-pandemic influenza and HPV vaccine uptake efforts, (2) addressing vaccine disparities in ethnic minority communities, and (3) supporting recent COVID-19 vaccination efforts.

Theme 1: Pre-Pandemic Influenza and HPV Vaccine Uptake Efforts
Zimmerman et al. [46] conducted a pre-post study to assess whether interventions tailored to individual practice sites increased influenza vaccination rates among high-risk children at inner-city health centers over two years. The authors found that FBOs saw the highest rates of vaccination compared to other practices and were associated with the highest rates of children obtaining the influenza vaccine. Similarly, Bond et al. [47] showed that FBOs in New York are uniquely equipped with resources to deliver health promotion programs to community members versus academic and governmental organizations, which resulted in high retention rates.
Kiser and Lovelace [48] assessed a national (US) collaboration between the Interhealth Health Program (IPH) at Emory University, the Department of Health and Human Services Partnership Center, the Centers for Disease Control and Prevention (CDC), and the Association of State and Territorial Health Officials to prevent the spread of 2009 H1N1 and seasonal influenza by leveraging community organizations (FBOs being one of them). The authors found that forming national partnerships is critical in mobilizing local community resources and organizations such as FBOs to improve vaccination efforts among underserved populations.
Regarding HPV vaccine uptake efforts, Lahjiani et al. [49] conducted a qualitative case study in the US to understand community perceptions of the HPV vaccination among both leaders and members of an African Methodist Episcopal (AME) church in Atlanta, Georgia. This study made use of a Social and Behavior Change Communication framework in order to increase the promotion of the HPV vaccination in the future. Focusing on findings related to church leaders, this church-based intervention found that leaders were amenable to (1) having more trust in the healthcare system and (2) viewing the HPV vaccine in a less stigmatized manner, instead promoting uptake of the vaccine among church community members. The authors stated that mistrust in the healthcare system by intervention participants was likely due to unethical treatment of study participants in the Tuskegee Syphilis Study. Conducting this study was important as HPV prevention within this specific church community has never been done before. As a result, this study serves as an important step for leaders of this church community to mobilize and promote the uptake of the HPV vaccine within the AME community. Similarly, Olagoke et al. [50] conducted a cross-sectional study in the US to assess the associations between three domains of religiosity (organizational, non-organizational, and intrinsic) and the intention to obtain HPV information and receive the HPV vaccine. This study found a positive association between the organization domain and the intention to seek HPV information. However, it was also found that information-seeking may not lead to vaccination. This study underscored the importance of engaging FBOs and empowering them to provide parents with accurate information regarding HPV vaccination to increase HPV vaccination rates.

Theme 2: Addressing Vaccine Disparities in Ethnic Minority Communities
Daniels et al. [51] conducted a randomized controlled trial in the US to examine (1) whether church-based vaccine education increased adult utilization of vaccinations in ethnic/minority communities, and (2) if churchgoers who are offered vaccinations in churches have higher vaccination utilization rates compared to non-churchgoers. The target population for this study was African American and Latino adults aged 65 and older living in San Francisco, California. This study showed the value of FBOs in decreasing the disparities in vaccination rates among racial/ethnic communities.
Santibañez et al. [6] discussed how CDC-FBOs collaborations played a key role in the response to pandemic influenza (2009). This vaccination effort focused on ethnic minority communities in the Minneapolis-St. Paul area. The Minnesota Immunization Networking Initiative (MINI) conducted vaccination clinics at places of worship (Churches, a Hindu Temple, mosques, a Buddhist monastery) and provided free influenza vaccinations. The collaboration of MINI with different FBOs helped address barriers to influenza vaccinations (access, mistrust, transportation) among underserved groups.

Theme 3: Supporting Recent COVID-19 Vaccination Efforts
Monson et al. [52] conducted a narrative review that showed how medical-religious partnerships are practical and valuable in mitigating the impact of COVID-19-related disparities in the US (e.g., using FBOs as COVID-19 testing sites and as potential COVID-19 vaccine sites). Dascalu et al. [53] conducted a case study in Romania to discuss the contributions of the Romanian Orthodox Church (ROC) in mitigating the impact of COVID-19; vaccination efforts being one. This study found that the ROC advocated against misinformation regarding both COVID-19 in general as well as the national vaccine campaign.
Rachmawati et al. [54] conducted a qualitative case study in Indonesia to assess the strengths of Indonesia's two largest Islamic FBOs and the challenges faced while conducting activities to mitigate the impact of COVID-19 nationally. The target population for this study were informants (the heads of the special units of both FBOs, government officials, etc.). An important finding of this study was that the Central Board of one of the FBOs provided support for COVID-19 vaccination implementation. Overall, the collaboration of FBOs with the government aid in mobilizing resources to help reduce the impact of COVID-19 in communities across Indonesia.
In contrast to the ten studies summarized above, it is important to note that Rujis et al. [55] conducted a qualitative study (grounded theory) in the Netherlands to determine the role of Protestant religious leaders in promoting acceptance or refusal of vaccination by members of the church. This study showed that the role of Protestant religious leaders in influencing the acceptance or refusal of vaccination was split into three subgroups-(1) those who do not recognize the need to address vaccination as congregation members already accept it, (2) those who focus on giving congregation members the choice, and (3) those who preach against vaccination. All three subgroups believe vaccination in the Netherlands should continue to be voluntary. Additionally, pastors are unwilling to promote vaccination on behalf of the authorities. Thus, this shows that using FBOs to promote vaccination in the Netherlands may not be effective because Protestant religious leaders are unwilling to promote vaccination and there is a low level of religiosity in the general population.

Discussion
This timely systematic review summarizes the opportunities for FBOs, built on key themes, to drive public health policy and action to support public health vaccine uptake efforts. Despite the recognized value of FBOs, they remain under-utilized in supporting routine vaccination, resulting in somewhat limited published studies on effectiveness for discreet areas of public health concern, such as vaccination uptake. However, FBOs have played a robust role in COVID-19 vaccine uptake in the US and globally [56,57]. Additionally, the COVID-19 pandemic has underscored the critical importance of going hyper-local to engage community-based organizations such as FBOs to increase vaccine confidence, allay vaccine concerns, and ultimately drive vaccination uptake. As such we also provide promising strategies that are being leveraged now to support COVID-19 vaccination. For instance, the All Dulles Areas Muslim Society (ADAMS) Compassionate Healthcare Network in Virginia is run by an interfaith team and is committed to providing community members with access to the COVID-19 vaccine [58].
Additionally, Faiths4Vaccines is a highly active group of religious leaders from across the United States which was established during the COVID-19 pandemic to promote vaccine equity. The organization is led by religions and medical leaders and has brought together over 1000 faith leaders across diverse communities in the United States to promote vaccine access and equity. They held 13 bi-weekly roundtables to support a knowledgeexchange for best practices, led by those who have utilized their house of worship as a vaccination site. Faiths4Vaccines had regular engagement with the White House Office on Faith based and Neighborhood Partnerships, the White House COVID-19 Task Force, the Center for Disease Control and Health and Human Services, as part of these bi-weekly calls.
Faiths4Vaccines convened the largest interreligious National Summit in the United States focused on vaccine access and uptake. The Summit connected over 800 registered local and national faith groups, medical professionals, and government officials to identify opportunities for faith leaders and institutions to identify mechanisms and collaboration opportunities to advance equitable vaccine acceptance and uptake. In addition, youth for faith initiative was established in June 2021, which consisted of a roundtable discussion showcasing how youths of faith are leading in their communities within the COVID-19 vaccination efforts. An interfaith clinic vaccination site was established in Washington D.C. The clinic hosted at the mosque was part of Washington, D.C.'s "Faith in the Vaccine Initiative", which has administered more than 4600 vaccines since February 2021. Lastly, as demonstrated by the evidence and promising findings in this review, partnering with FBOs is particularly critical to engage traditionally underserved, marginalized, and hard-to-reach populations, which can help address health and specifically vaccination disparities that have only widened during the COVID-19 pandemic.
Similarly, the Jerusalem Impact Vaccination Initiative convened leaders of the Jewish, Christian, Muslim, Druze, and Bahá'í Faiths of the Holy Land in November 2021, to develop an action plan on improving vaccination coverage and community resilience. Through the President of the State of Israel, this initiative widened its scope to similar dialogues in Germany and Switzerland.
This review found that previous public health efforts that partnered with FBOs fell into four general themes. All of these themes are critically important in the context of barriers to vaccine uptake barriers. While there is a strong evidence base to support the benefits of receiving routine vaccinations across the life-course, there is an equally strong literature base documenting disparities in the acceptance and uptake of vaccines among individuals from racial and ethnic minority populations [59,60].
Vaccine hesitancy had steadily increased in the United States prior to the COVID-19 pandemic and has been amplified further during the pandemic [61]. Vaccine hesitancy is described as one's confidence in the safety and efficacy of the vaccines, complacency towards vaccine uptake/completion, and convenience in accessing the vaccine. The reasons for hesitancy are varied, but many include the following; (1) concerns about perceived safety, (2) skepticism about the trustworthiness of the source(s) of vaccination recommendations, (3) exposure to misinformation and disinformation, (4) immunization considered a low priority, (5) perceived low risk of illness, (6) limited knowledge and health literacy about the disease, (7) difficulty accessing services, (8) clinician bias, (9) cost, or (10) personal, cultural or religious beliefs discouraging vaccination [62,63]. According to a 2019 national survey conducted by the American Academy of Pediatrics, >1 in 4 parents reported hesitancy about influenza vaccinations [11]. Only 1 in 4 parents believed the influenza vaccine was effective and 1 in 8 parents had concerns about the safety of both influenza and other childhood vaccines.
Studies have further documented a pattern of racial and ethnic minority persons being less likely to receive the influenza vaccination, with socioeconomic and clinician/health care system factors as main predictors of poor uptake. Research on HPV vaccine uptake shows a similar pattern of racial and ethnic minority persons being less likely to initiate or complete the series [64]. A survey conducted by the Public Religion Research Institute conducted in March 2021 found that 36% of Black Protestants and 33% of Hispanic Americans who are vaccine hesitant say one or more faith-based approaches would make them more likely to get vaccinated [13].
The COVID-19 pandemic has illuminated global vaccine uptake disparities that require innovative public health strategies. Utilizing a multipronged approach to enhance vaccination rates with both strategic and creative approaches can aid in advancing science. Indeed, effective measures and trusted resources, such as FBOs, are essential to addressing and reducing misinformation, building community trust, and promoting widespread vaccine dissemination, population level uptake, and adherence to vaccination protocols. Upstream factors (e.g., interpersonal, community, health system, policy), relevant cultural and historical factors associated with individual beliefs, risk perceptions, and behavior across multiple levels (e.g., individual, community, etc.) must all be considered. Importantly, policy guidance is needed to address misinformation, distrust, and hesitancy regarding the uptake of vaccines (e.g., COVID-19, pneumococcal, influenza, hepatitis B, human papillomavirus (HPV)), especially in populations at increased risk for morbidity and mortality due to long-standing systemic health and social inequities and chronic medical conditions.
Notably, we also found that the majority of research exploring the role of FBOs and faith-based engagement, occurred in the US (14 of 26), other countries examined came up singularly: Barbados, Israel, Indonesia, Romania, Germany, Ethiopia, Ghana, Southeast Asia, broadly. Given the disproportionate volume of research focused on efforts in the US, comparing findings across countries based on available evidence is challenging. However, consistently, while the value of FBOs and faith-based engagement is identified particularly in supporting underserved and traditionally marginalized populations, most studies underscored the importance of coordination with ongoing vaccination efforts so as to not undermine or duplicated efforts, but rather enhance and build upon them. No discernable differences were identified between how FBOs are engaged across countries included in the studies that were captured in this review, with the exception of Rujis et al. [56] which focused on the role of Protestant religious leaders in the Netherlands, which found that in this case, engaging Protestant religious leaders to support vaccination efforts may be ineffective as leaders were unwilling to promote vaccination, and there was a low level of religiosity in the general population. This provides important insights moving forward in that the potential impact of FBOs and faith-based engagement in supporting vaccination efforts may be determinant on the local level faith-community's buy-in and willingness to engage on this issue as well as the level of religiosity in the community.
It is important to acknowledge the limitations in this review. First, the intersection between faith-based organizations and vaccination is complex and multifaceted, spanning the breadth of vaccine education, vaccine hesitancy, health equity, vaccine programming for communities of faith, the role of faith-based organizations in supporting vaccine efforts in communities beyond their own, and others. Moreover, improving vaccination rates in and of itself is a complex subject, with limited generalizability across different contexts (ex. emergency response; primary care; domestic vs. global settings) and unique challenges with uptake of specific vaccinations among different target populations (ex. MMR vs. HPV vs. COVID-19 vaccine). Lastly, the focus on FBOs is, at times, in danger of glossing over racial/ethnic inequalities in health, when the intersection of religion and race/ethnicity is important to consider in explicit detail.
This review did identify important gaps in the literature. First, the importance of the role of FBOs in vaccination efforts among pediatric populations has received little attention in the literature. Additionally, there is a lack of evidence and outcome-based research on the role of FBOs in vaccination uptake efforts, particularly in assessing the effectiveness of health programs, community participation, and project continuation. Similarly, the narrow field of literature is dominated by studies of pandemic and non-pandemic influenza vaccination in the US. Therefore, there is a lack of understanding of how FBOs affect the implementation of programs in various settings and policy contexts. Future research should also further examine any differences or commonalities in the role of FBO and faith-based engagement across high income and low-and middle-income countries.
In summary, the global scale of disruptions to routine vaccination due to the COVID-19 pandemic highlights the risk of potential VPDs outbreaks in the future and the urgent need for "catch-up vaccination strategy implementation for vulnerable populations and ensuring vaccine coverage equity and health system resilience" [65]. FBOs can and should be a part of this solution based on their solid track record of previous partnerships that have led to public health successes.

Conclusions
This review found that generally FBOs play a vital role in global vaccination efforts, represent significant potential for effective public health and vaccination campaigns, and can help improve vaccination efforts, particularly within traditionally underserved populations. Based on the literature, it is recommended that FBOs be positioned to build trust with communities, activate existing networks, draw on expertise, involve community partners, and resolve conflict. As trusted members of communities, FBOs allow public health interventions to be modified so that individuals are receptive to the messaging. With an established relationship of trust, individuals will be inclined to participate in the vaccination campaigns introduced by their FBOs. Vaccination and policy stakeholders should explore engaging with, enabling, and resourcing FBOs in implementing local vaccination programs and practices to achieve and maintain high vaccination coverage rates.
Supplementary Materials: The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/vaccines11020449/s1, Figure S1: PRISMA Diagram Showing Selection of Articles, Table S1: Sample of quality assessment tool for systematic reviews and metaanalyses by the National Heart, Lung, and Blood Institute (NHLBI) for Sheikhi et al. Table S2: Sample of quality assessment tool for observational cohort and cross-sectional studies by the National Heart, Lung, and Blood Institute (NHLBI) for Olagoke et al. Table S3: Sample of quality assessment tool for controlled intervention studies by the National Heart, Lung, and Blood Institute (NHLBI) for Daniels et al. Table S4: Sample of quality assessment tool for case series studies by the National Heart, Lung, and Blood Institute (NHLBI) for Dascalu et al.

Data Availability Statement:
No new data were created or analyzed in this study. Data sharing is not applicable to this article.

Conflicts of Interest:
Alexandra Bhatti is a current employee of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA, and holds equity interest in Merck & Co., Inc., Rahway, NJ, USA. Inon Schenker is CEO of Impact Vaccination, a consultancy firm pre-qualified by COVAX for vaccination capacity-building, Jerusalem, Israel.